(1) Field of the Invention
This invention relates to a catalyst composition for organic asymmetric synthesis, a catalyst solution comprising the catalyst composition, and a process for preparing an optically active epoxide by catalytic asymmetric epoxidation.
The catalyst composition of the present invention is useful for various organic asymmetric syntheses. For example, it exhibits a high catalytic activity for asymmetric epoxidation of enones and gives epoxides having an enhanced optical purity.
(2) Description of the Related Art
As for catalysts for organic asymmetric syntheses, a catalyst solution has been heretofore proposed for asymmetric epoxidation in Japanese Unexamined Patent Publication No. H10-120668, which comprises (A) lanthanum isopropoxide, (B) a binaphthol derivative represented by the following general formula (6): ##STR1##
wherein R.sup.14 is hydrogen or a hydroxymethyl group, and * signifies that the carbon atom adjacent thereto is optically active, (C) a molecular sieve 4A, and (D) tetrahydrofuran.
However, when the catalytic asymmetric epoxidation is conducted by using tert-butylhydroperoxide (hereinafter abbreviated to "TBHP") as an oxidizing agent and, for example, at room temperature for 30 minutes, an epoxide with a low optical purity of 73% is obtained in a low yield of 86%. If the catalytic asymmetric epoxidation is conducted by using a special oxidizing agent, i.e., cumene hydroperoxide (hereinafter abbreviated to "CMHP") and, for example, for at least 6 hours, then, epoxides with an optical purity of 83 to 94% are obtained in a yield of 78 to 98% (J. Am. Chem. Soc. Vol. 119, No. 9, 1997, p2329-2330).